The Collector's Edition guide for Mass Effect 3, on page 263, has an error that should be corrected. It details the requirements necessary to bring about a peace between the Quarian and Geth, at the end of the mission, Priority: Rannoch. One of the requirements it states is to have killed the heretics during Legion's loyalty mission. This is actually not correct, as it is possible to bring about the "peace ending" between the two by gaining Legion's loyalty, regardless of whether you chose to kill the heretics or rewrite them. Proof being I just did as much.